Boiler flue cleaner



Dec. 17, 1940. c. ELM

BOILER FLUE CL EANER Filed Feb. 21, 1939 Patented Dec. 17, 1940 rs STA- 3 Claims.

This invention relates to means for freeing the tubes of water-tube boilers of the deposit of solids therein and special reference to the construction of hammer means for. breaking up this hard deposit.

The objects of my invention are'to provide a multiple pneumatic hammer adapted to operate on separate parts of the tube simultaneously; which will be entirely automatic; in which the pressure will be balanced on the two sides of the pistons; in which two free pistons are employed, and in which each piston acts as the control or valve for the other piston and in which each acts intermittently and alternately with the other.

With the above objects outlined and with other objects in view as will be apparent as the nature of the invention is studied, the present invention resides in the combination and arrangement of parts and in the details of construction illustrated in the accompanying drawing, in which- Fig. 1 is a longitudinal section of my improved duplex pneumatic hammer; Fig. 2 is a cross-section thereof taken on the line 2--2 in Fig. 1; Fig. 3 is an end-elevation thereof; Fig. 4 is a side elevation of the operating end thereof; Figs. 5, 6 and 7 are diagrammatic illustrations showing the motion of the two pistons and the automatic control which each exercises over the other, the full lines being passages in action while the broken lines represent the idle passages, and in which Fig. 5 shows the lower piston stationary while the upper piston is being withdrawn to its idle position, Fig. 6 shows the positions at a quarter stroke later, and Fig. 7 shows the upper piston fully withdrawn and idle while the lower piston is beginning its operative outward stroke.

Similar numerals of reference refer to similar parts throughout the several views.

The inside of tubes of boilers becomes heavily incrusted with an extremely hard scale which, if allowed to accumulate, very materially reduces the efliciency of the boiler by resisting the free transfer of. the heat of the fire to the water in the tubes. This scale incrustation may only be bro-ken by suitable hammer means.

Referring to the drawing, it will be seen that the body I of my improved pneumatic hammer is mounted on the end of a suitable rod 2 by which it is manipulated within the boiler tube, and through whose central passage 3 the operating airis supplied under suitable pressure. This head I comprises a cylindrical body slightly smaller than theinternal diameter of the tubes of the boiler. Two :cylindrical cavities 4 and 5 are provided within the body I. These cavities 4- and 5 are in every way similar and areclosed at their rear end and are reduced in diameter attheir forward end by means of sleeves 6, or otherwise. A pair of free pistons 'I and 8 are mounted in the cylinders 4 and 5, respectively, each said piston being provided with .a forward cylindrical extension v9 mounted to reciprocate within the sleeves Band provided with conical ends It.

- The forward end of. the body I is provided with a central bracket 'II extending across the body I in the plane at' right-angles to the plane in which the axes :of the. cylinders 4 and 5 lie. Two pivot pins I2 and I3 are mounted in the bracket II and each extends outward on each side thereof. Four hammers are mounted on the said pins l2 and I3, one on each side of said bracket II. The hammer It is mounted on one end of the pin I2 and the hammer IS on the other iend'thereofig while the hammers I5 and H are correspondingly mounted on the two ends of the pin I3. Each of the said hammers is adapted to be swung outward on its pivot pin I2 or I3 under the impulse of the respective pistons when the conical end It passes outward from the body I and enters the space between the inner 'endsof saidrhammers, forcing them outward. Each hammer has a head It having a sharp edge I9 adapted. to give the scale in the boiler tube a heavy blow to break it into small bits.

The body I is provided with an inlet passage 29 (Fig. 2) leading from the inlet passage 3 to the longitudinal center where it connects with two branch passages 2| leading to the inlet ports at the longitudinal center of each of the two cylinders 4 and 5. Also an oppositely positioned exhaust passage 22 leads from the forward or hammer end of the body I inward to two branch exhaust passages 23 which lead therefrom to exhaust ports at the longitudinal center of each of the said two cylinders 4 and 5. As seen in Fig. 2 the said passages 20 and 22 are in differ- .ent positions in relation to the two cylinders, and the branches 2| and 23 thereof lead to different points in the circumferences of the said cylinders, but, as seen in Fig. 1 all these ports are in the longitudinal central plane of the said cylinders 4 and '5. 50

Now the cylinder 4 is provided with two inlet valve ports 24 and 25 located on each side of and suitably spaced'from the central inlet port 26, opening into the inlet branch passage 2I thereof, and these ports are in axial valinement there- 55 with. Similarly the cylinder 5 is provided with two inlet valve ports 21 and 28 correspondingly located on each side of the inlet port 29, opening into the other branch passage 2|. Also, the cylinder 4 is provided with two exhaust valve ports 36 and 3| on each side of the exhaust port 32, opening into the branch exhaust passage 23; while the cylinder 5 is provided with two exhaust valve ports 33 and 34 correspondingly located on each side of the exhaust port 35. The above valve ports 24, 21, 3|! and 33 lie in the same transverse plane a suitable distance to the left of the central transverse plane in which the ports 26, 29, 32, and 35 lie, while the valve ports 25, 28, 3| and 34 lie in a plane positioned an equal distance to the right of the central plane. The cylinder 4 is provided with two inlet ports 36 and 31 opening thereinto at the extreme left and right ends thereof respectively, while the cylinder 5 has two corresponding inlet ports 38 and 39. Similarly the cylinder 4 has two, ex haust ports 40 and 4| opening thereinto near the extreme left and right ends thereof respectively, while the cylinder 5 has two correspond: ing, exhaust ports 42 and 43.

The body I also has aseries of passages each of which connects one valve inlet port of one cylinder with one inlet port of the other cylinder, or one valve exhaust port ofone cylinder with one exhaust port of the other cylindensas follows: The passage 44 connects the left valve inlet port 24 of cylinder 4 with the right inlet port 39 of cylinder 5; the passage 45 connects ports 25 and 38; the passage 46 connects ports 21 and 36; the passage 41 connects ports 28 and 31; and the passage 48 connects the left exhaust valve port 36 of cylinder 4 with the left exhaust port 42 of cylinder 5; the passage 49 connects ports 3| and 43; the passage 50 connects ports 33 and 4|; and the passage 5| connects ports 34 and 40. It will be observed thatif the inlet passages from one cylinder cross each other in reaching the proper port of the other cylinder then the exhaust passages do not cross in passing from the same first cylinder to reach the proper port of the other cylinder, and vice versa.

Referring, again to Fig. 1, it will be observed that each of the pistons I and 8 is provided with two series of grooves 52 arranged around their circumferences (Fig. 2) and that each said groove 52 is connected to the diametrically opposite groove 52 by means of a relief passage 53 extending across the piston; thus the pressure is balanced on the two opposite sides and excessive wearof the piston is avoided. The two sets of grooves are separated in the center of the pistons by a suitable distance and also do not extend to the front or rear ends of the two pistons, thus being entirely insulated from each other and from the cylinders 5 and 4 in which the pistons reciprocate.

The'spacing of the valve ports 24 and 25 from 26, of 21 and 28 from 29, of 30 and 3| from 32,

and of 33 and 34 from 35, and the space on the piston between the two sets of grooves 52 are coordinated so that only one of each pair of valve ports is connected with the intermediate inlet or exhaust valve port.

Since the grooves 52 extend around each of the pistons it is evident that the pistons may rotate on their axes freely without interfering with the valve action of the pistons in controlling the longitudinal motion of their respective mates. 1 Q

The action of each piston in acting as a valve for the other piston is illustrated for one-quarter cycle in diagrammatic form in Figs. 5, 6, and 7, in which the pressure or inlet ports are arranged in the centers of the diagrams, while the exhaust ports are arranged at the top and bottom thereof; also the passages which are momentarily active are shown in full lines while those which are simultaneously idle are shown in broken lines.

In Fig. 5 it will be seen that the piston 8 is stationary at the left end of its travel in cylinder 5, thus opening the connection between the inlet passage 20 through its branch 2|, port 29, groove 52, with the right-hand inlet valve port 28 and passage 41 to the inlet port 31 at the right-hand end of the cylinder 4, and, simultaneously, the exhaust passage 22 is connected through the branch 23, port 35, groove 52 with the right-hand valve exhaust port 34 and passage 5|- to the left-hand exhaust port 4|]. of the said cylinder 4,.thus the piston I is driven towards the left in the cylinder 4. Also the piston 1 while movingtowards the left momentarily keeps the said piston 8-in such stationarycondition because the inlet passage 20 is connected through branch 2|, port 26, groove 52 with port 24, passage 44 to the right inlet'port 39 of the cylinder5, and the exhaust passage 22 is open through the branch23, port 32, groove 52, port 38, passage 48 to, the left-hand exhaust port 42 of the cylinder'5. 1

As thepiston 1 moves towards the left (Fig. 6) the piston 8 stays in its left-hand position because the inlet port 39 and the exhaust port 42 have been closed by the motion of the piston l andthe opposite inlet port 38 and exhaust portq43i have not yet been opened, while the piston; l continues in left-hand motion under the same conditions as shown in Fig. ,5.

But, as soon as thepiston 'I has moved far enough towards the left (Fig. 7), it then starts the piston 8 towards the right by admitting air pressure from the passage 26 by the branch 2|, port 26, groove 52, port 25, passage 45 to the left inlet port 38 of thecylinder 5 and simultaneously opens the exhaust passage 22 by thebranch 23, exhaust port 32, groove 52, port 3|, passage 49 to the right-hand exhaust port 43 of the cylinder 5, thus impelling the piston 8 towards the right, while the piston 1 stays in its left-hand position under the continued pressure due to the closing of itsinlet and exhaust ports by the motion of, the said piston 8.

The balance of the cycle of motion of the respective pistons will be readily understood from the above. The piston 1 remains stationary while the piston 8 continues in motion towards the right; then the piston 8 remains stationary while the piston lstravels towards the right; the

piston I then remains stationary at the right while the pistonj travels towards the left; then the piston 8 remains stationary at the left and the cycle begins again.

,Since the whole left-hand area of each piston is exposed to the air. pressure it follows that the energy of the outward blow of the piston end 16 on two of the hammers l4 and I5 or l6 and I1 is at its maximumvalue, but, since the area exposed to the air pressure at the righthand end is greatly reduced, it follows that its retractile .motionlis gentler, thus reducing the shock. Thefseveral hammers |4|| are provided with suitable springs adapted to draw them towards each other upon the withdrawal of therespective conical ends l0 of the pistons.

Also, it will be noted that the several pistons are free to rotate upon their longitudinal axes, thus reducing the wear thereon and serving to maintain a truly cylindrical shape of the pistons and cylinders. This is accomplished by the fact that the cylinders are provided with the grooves 52 as above described and that the grooves are separated from each other.

Thus it will be seen that I have provided an entirely automatic hammer means whereby the scale may be broken away from the inside of the boiler tubes; that the hammers are arranged in pairs, each hammer of a pair acting in opposite directions simultaneously on separate parts of the scale, and the other pair acting alternately on other two separated parts of the scale, thereby attacking the scale in the severest manner and breaking it into small chips. The rod 2 with the above-described hammer body I onits end may also be oscillated about its axis as it is moved forward to insure the engagement of every portion of the tube by the several hammers.

It is, of course, to be understood that variations in the construction of my improved pneumatic hammer may be made without departing from the spirit of my invention as outlined in the appended claims.

Having, therefore, described my invention, what I claim and desire to secure by Letters Patent, is:

1. In a duplex alternately intermittent fluid motor, the combination with a body; of means for conveying a fluid under pressure thereto; a pair of cylinders formed therein; a pair of free reciprocating elongated pistons in said cylinders; an inlet and an exhaust port in each of said cylinders and located in the central transverse planes thereof, with passages leading respectively to the fluid supply and to an exhaust outlet; a second set of two inlet and two exhaust valve ports in said cylinders located in two transverse planes axially spaced on each side of said central plane of said first ports; end inlet and exhaust ports adjacent each end of each of said cyliinders; pairs of axial grooves in each of said pistons located in longitudinal alinement but spaced axially from each other and adapted to connect the central inlet and exhaust ports with the respective inlet and exhaust valve-ports as the pistons reciprocate; and passages in said body, each connecting one said inlet or exhaust valve-port with an end inlet or exhaust port of the other cylinder, whereby each piston controls the motion of the other piston.

2. A fluid motor as set forth in claim 1, characterized by the circumferential separation of the inlet port of each cylinder from the exhaust port thereof; by the corresponding separation of the inlet and exhaust valve-ports; and by the circumferential separation of the pairs of grooves in said pistons, whereby one pair of grooves is adapted to connect the inlet port with one or the other inlet valve-port and another pair of grooves is adapted to simultaneously connect the exhaust port with one or the other exhaust valve-port.

3. A fluid motor as set forth in claim 1, characterized by the circumferential separation of the inlet port of each cylinder from the exhaust port thereof; and wherein the inlet valveports lie in the same axial plane as the inlet port and the exhaust valve-ports lie in the same axial plane as the exhaust port; and wherein the axial grooves in said pistons comprise a continuous series of separated grooves arranged around the pistons, whereby the pistons are free to turn axially in the cylinders, the grooves of one set being in axial alinement with the grooves of the other set, each groove being connected to the diametrically opposite groove by passages through the pistons, whereby the transverse pressure of the fluid on the pistons is equalized and the wear thereof reduced.

CHARLES ELM. 

